GB1266460A - - Google Patents

Abstract

1,266,460. Automatic temperature control systems. OWENS-CORNING FIBERGLAS CORP. March 14, 1968 [March 31, 1967], No.38377/70. Divided out of 1, 221, 864. Heading G3R. An apparatus for heat-treating material comprising a heating zone with a material inlet and outlet and means for sensing the temperature of a material in the zone and regulating the amount of heat supplied by a heating means, also has a means for detecting a predetermined change with respect to time in the temperature which inhibits the regulating effect of the control means outside of a determined band. The material may pass through a succession of heating zones each con- trolled and supplied with heat independently and a signal from the first zone, after a delay may, modify the control of the second zone et seq. The forehearth of glass melting furnace 110 has a plurality of zones 1-3, the temperature in each zone being sensed by a thermocouple e.g. 140 and fired by separately controlled gas or oil fired burners. If a cool mass of material flows into the forehearth the thermocouple 140 will sense a reduced temperature and hence will normally supply a signal to controller 150 which increases the rate of firing of burners 120. Such signal is therefore passed through an analyzer 160 which may be a computer which measures the temperature sensed by thermocouple 140 at periodic intervals e.g. every two seconds, as the temperature changes, until a predetermined level is reached when the signal is forwarded to controller 150 to prevent a further increase in fuel supply. Alternatively the computer may measure the rate of change of temperature and provide a modifying signal to a controller 150. A modifying signal will only be sent to the controller in response to rates of change for total amounts of change above a determined level. Transient changes effected by small masses of incompletely melted material will not modify the action of the controller 150. The signal from circuit 160 may also be utilized to effect a holding action on the controllers relating to burners 122, 124 by way of delay circuits 170, 172 respectively, such delays being related to the time of passage of the incompletely melted material. An over-riding control (not shown) is incorporated in the system so that in start up and shut down periods the analyzer 160 is inoperative. In a modification, to offset a rise in temperature during a period when the rate of change is being measured, the modifying signal may reduce the fuel supply by a determined amount. The arrangement may be utilized to provide a more even heating and curing of strips of material having irregularly occurring portions or increased or decreased masses not requiring the same heattreatment as the carriers to which they are attached.